Vaccines are one of the greatest inventions of the last 150 years. They've all but eradicated deadly diseases like smallpox, polio, and measles from most of the world. The same vaccines that allowed civilization to flourish in the twentieth century, however, have become a political hot button in the twenty-first. What changed? It's possible that a whole generation grew up without witnessing firsthand the horrors of deadly contagious disease on children, and so they never understood the value of vaccination.

Let's take a refresher course and look at what vaccines are, how they work, and several myths surrounding their use.

How do vaccines work?

Vaccines are a single or multiple dose treatment designed to provide a person with immunity from a particular disease. They work by exposing you to a weakened version of a pathogen, like a flu virus. Your body's immune system remembers the pathogen's characteristics and develops the necessary antibodies to resist the pathogen if exposed to it in the wild.

After early experiments with smallpox vaccine, researchers in the twentieth century quickly invented vaccines for measles, mumps, rubella, polio, and diphtheria along with a variety of other illnesses. The defeat of these diseases was not just due to science - it was also due to public health officials who presented a united front in developing and applying vaccines to the population, greatly increasing the quality of life during childhood and preventing unnecessary deaths. In an era of relative safety, when many deadly childhood diseases are kept at bay, many people are questioning the legitimacy of these vaccines, leading some parents to fear the very thing that might save their child's life.

Here are a few myths about vaccines — myths that could prove deadly.

Myth: Vaccines can give your child autism or other disorders.

Fact: No scientific study backs this claim, and the study that seeded the claim is now regarded as fraud.

In the 1998 Lancet article Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children, Dr. Andrew Wakefield suggested a link between the common Measles, Mumps, & Rubella (MMR) vaccine and gastrointestinal disorders that later developed into a general connection between MMR and autism. The research was unable to be reproduced and it was later found that Dr. Wakefield's research was paid for in part by lawyer's representing clients in an effort to sue vaccine manufacturers and that Wakefield himself patented a Measles vaccine in 1997. The Lancet officially retracted the article in February 2010. Wakefield is no longer a licensed physician in the US or UK , but moved to the United States and founded the Thoughtful Life Care Center for Children, only to resign as Executive Director after the Lancet retracted the seminal 1998 article.

Presidential Candidate Michele Bachmann recently suggested that the HPV vaccine, often given to individuals between the ages of 11 and 12 to prevent sexually transmitted diseases, caused mental retardation, quickly leading the American Academy of Pediatrics to deny the suggestion and Bachman herself to step away from the claim. This statement, however, shows the power inherent in a sentence not backed with evidence, especially when said on a national stage.

Myth: Vaccine additives are harmful.

Fact: While the components may sound scary, vaccine additives offer a preventative advantage.

The mercury-based additive thimersol was a key talking point in the MMR vaccine and autism controversy. Thimersol is present in vaccines in order to prevent contamination of bacteria. Although a definitive link to autism was never established, Thimersol was nevertheless removed from most childhood vaccines as a precaution as of 2001. Another vaccine component, monosodium glutamate (the additive MSG often found in foods), is included in order to stabilize the vaccine through changes in temperature and increase shelf life. This is an especially worthwhile additive when transporting vaccines to other countries.Aluminum salts are also included, as they increase the body's immune response reaction, allowing for a smaller quantity of vaccine itself to be administered. Aluminum and MSG are common in our food and environment, and while they may pose limited health issues, the CDC feels that they are safe enough to be administered in vaccine

Myth: Skipping childhood vaccines is the safe and cautious move.

Fact: You are exposing your child to diseases that humanity spent decades trying to eradicate.

Dr. Wakefield's work has convinced parents that they should prevent their children from receiving the MMR vaccine in the UK and worldwide. Thousands of individuals worked throughout the early twenteith century to rid most of the world of smallpox, polio, and measles. Without vaccines, these diseases could recur — and easy worldwide travel in the twenty-first century could jumpstart an outbreak. Additionally, non-medical exemptions for several childhood vaccines have become commonplace, leading to geographic outbreaks of oft-vaccinated diseases, such as the recent with a recent measles outbreak observed in San Diego, California in 2008.

Prior to widespread vaccination in the twentieth century, children were lucky to survive past the age of 10. Vaccines give a chance for every child to survive — the Center for Disease Control's recommended childhood vaccine schedule can be perused here. Un-vaccinated children pose a threat to themselves (for example, if they are exposed to tetanus while playing), as well as a greater societal and public health risk if they pass a disease along to other people.

Deadly diseases are real - that's why the vaccines exist. Preventing childhood vaccines can expose everyone to horrors long since eradicated in most parts of the world. Giving children vaccines is like teaching them fire safety: It could save their lives, and the lives of everyone around them, too.

Images courtesy of the AP. Source documents are linked within the article.